Stoves Oven burning yellow

[caveman2]

My missus cleaned the 2 year old Stoves gas oven today and failed to cover the burner assembly. As a result some of the jetsa are burning yellow and the and it is continually sparking.
I have just about managed to get my head into the oven and can see the assembly and to be fair there doesnt appear to be any debris on top although something may have entered the jets. But the yellow now only burns at the two extreme end around what appears to be a senson and the sparkers.
Could deposits on these be the cause of the yellow flames and how long would it normally take to wear off or could I clean them with something. BTW does the door come off to give easier access and does the metal cowl infront of the assembly slide off again to give visual access to the jets.
Cheers

 

[caveman2]

Ok so I have managed to remove cowl and made accessing the burner assembly. I have given that a clean up (care taken) and where some Jif existed I have used a pin.
The result is a nice even blue flame along the burner, But where the flame surrounds the ignitor it turns to a yellow flame which when the cowl is replaced gives the impression of the gas burning yellow.
So I ask is it usual for the flame around the ignitor to turn yellow?